Abstract
S-Sulfenylation is a post-translational modification with a crucial role in regulating protein function. However, its analysis has remained challenging due to the lack of facile sulfenic acid models. We report the first photocaged cysteine sulfenic acid with efficient photodeprotection and demonstrate its utility by generating sulfenic acid in a thiol peroxidase after illumination in vitro. These caged sulfoxides should be promising for site-specific incorporation of Cys sulfenic acid in living cells via genetic code expansion.